A known apparatus for discharging a fixed amount of liquid operates to decompress a compressed gas supplied from a compressed gas source to a certain pressure and to distribute or dispense a liquid material. In that type of known apparatus, however, accuracy in an amount of the liquid material distributed or dispensed is insufficient. This may cause, for example, problems that, when a semiconductor chip is bonded to, e.g., a lead frame or a printed board, the chip is peeled off due to an insufficient amount of adhesive discharged, or short-circuiting is generated due to an electroconductive adhesive discharged in an excessive amount.
In view of the above-mentioned problems, the applicant has proposed a dispenser comprising a pressure reducing valve for decompressing a compressed gas supplied from a compressed gas source, a solenoid valve equipped with a timer for controlling an amount of the decompressed gas passing therethrough, and a dispensing nozzle for quantitatively distributing or dispensing a liquid material, which is stored in the dispensing nozzle, with the gas supplied through the solenoid valve, the dispenser discharging the fixed amount of the liquid material by directly pressing the surface of the liquid material, which is stored in the dispensing nozzle, with the compressed gas, wherein a buffer tank storing the compressed air and having a larger inner volume than the dispensing nozzle is disposed midway a line extending from the pressure reducing valve to the solenoid valve (Patent Document 1).
Also, there is proposed an applicator for applying an application material in a syringe to a printed board through a discharge nozzle by supplying compressed air under a predetermined pressure from a regulator, which is communicated with a compressed air source, to the syringe for a predetermined time with switching of a discharge valve, wherein the apparatus includes a pressure tank communicating with the regulator, storing the delivered compressed air, and supplying the compressed air to the discharge valve side (Patent Document 2).
In any of the above-described apparatuses, the buffer tank (pressure tank) is disposed to abruptly raise the pressure inside the syringe immediately after the valve opening for the discharge. With the action of the buffer tank, a high pressure can be obtained in a shorter discharge time than that in an apparatus not including the buffer tank. Accordingly, the pressure required to provide the desired discharge amount can be obtained in a shorter time and the discharge operation can be performed at a higher tact.